全文获取类型
收费全文 | 1281篇 |
免费 | 62篇 |
国内免费 | 7篇 |
专业分类
化学 | 968篇 |
晶体学 | 15篇 |
力学 | 6篇 |
数学 | 199篇 |
物理学 | 162篇 |
出版年
2023年 | 9篇 |
2022年 | 21篇 |
2021年 | 28篇 |
2020年 | 20篇 |
2019年 | 33篇 |
2018年 | 15篇 |
2017年 | 15篇 |
2016年 | 38篇 |
2015年 | 29篇 |
2014年 | 39篇 |
2013年 | 55篇 |
2012年 | 62篇 |
2011年 | 69篇 |
2010年 | 48篇 |
2009年 | 37篇 |
2008年 | 82篇 |
2007年 | 60篇 |
2006年 | 64篇 |
2005年 | 68篇 |
2004年 | 61篇 |
2003年 | 47篇 |
2002年 | 35篇 |
2001年 | 22篇 |
2000年 | 21篇 |
1999年 | 14篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 23篇 |
1995年 | 14篇 |
1994年 | 16篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 15篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 18篇 |
1987年 | 8篇 |
1986年 | 16篇 |
1985年 | 20篇 |
1984年 | 24篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1978年 | 17篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1971年 | 6篇 |
排序方式: 共有1350条查询结果,搜索用时 31 毫秒
11.
Israel Vainsencher 《Bulletin of the Brazilian Mathematical Society》1996,27(2):217-232
We show the family of tangent flags to smooth quadric hypersurfaces extends to a flat family parametrized by the variety of complete quadrics. This answers a question posed by S. Kleiman.Partially supported by CNPq-Brasil. 相似文献
12.
13.
Israel Vainsencher 《manuscripta mathematica》1989,64(1):121-126
LetX be a smooth, projective curve of genusg defined over a finite field. Then there exists a finite extension fieldk=F
q
such that, for all sufficiently largen, (1)X imbeds in P
n
in such a way that the set of pointsx ofX mapped via Frobenius into the osculating hyperplane ofX atx is the support of a positive divisor and (2) the numberN of points inX(k) satisfies
相似文献
14.
Elliott H. Lieb Israel M. Sigal Barry Simon Walter Thirring 《Communications in Mathematical Physics》1988,116(4):635-644
LetN(Z) denote the number of electrons which a nucleus of chargeZ can bind in non-relativistic quantum mechanics (assuming that electrons are fermions). We prove thatN(Z)/Z1 asZ.Research partially supported by the NSERC under Grant NA7901 and by the USNSF under Grants DMS-8416049 and PHY 85-15288-A01 相似文献
15.
16.
P. Goya A. Martinez C. Ochoa M. Stud M.L. Jimeno C. Foces-Foces F.H. Cano M. Martinez-Ripoll 《Tetrahedron》1985,41(15):3105-3116
Bisthiadiazinylmethane derivatives obtained from 1,2,6-thiadiazine 1,1-dioxides and formaldehyde, undergo unusual intramolecular cyclizations to thiadiazino [4,3-g] [2,1,3] benzothiadiazine tetraoxides. The structures of the newly synthesized compounds are discussed on the basis of 1H and 13C-NMR data and X-ray analysis. 相似文献
17.
18.
Asymmetry and magnetism in bis(oximato)-bridged heterobimetallic compounds: a computational approach
Cano J Rodríguez-Fortea A Alemany P Alvarez S Ruiz E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(2):327-333
A density functional study of exchange coupling was carried out for a series of heterobinuclear oximato-bridged transition metal complexes. Model calculations were used to examine the influence of the electronic configuration of the metal atoms on the coupling constants. This analysis was complemented by a study of the variation of the coupling constant with the most usual structural distortions within this family of compounds. The influence of the nature of the terminal ligands as well as that of the symmetry on the bridge were also investigated. 相似文献
19.
20.
Thermal behaviour of a polyhedral oligomeric silsesquioxane with epoxy resin cured by diamines 总被引:1,自引:0,他引:1
Ramírez C. Abad M. J. Barral L. Cano J. Díez F. J. López J. Montes R. Polo J. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):421-429
A new material belongs to the family of polyhedral oligomeric silsesquioxanes, the 1-(3-glycidyl) propoxy-3,5,7,9,11,13,15-isobutylpentacyclo-[9.5.1.1(3,9).1(5,15).1(7,13)]octasiloxane
(glycidylisobutyl-POSS) is characterized by differential scanning calorimetry, thermogravimetric analysis and atomic force
microscopy. Epoxy systems based on diglycidyl ether of bisphenol A (DGEBA) cured with the diamines, 4,4'-diamine-diphenylmethane
(DDM) and 1,4-phenylenediamine (pPDA), were kinetically studied by differential scanning calorimetry in isothermal and dynamic
modes. The thermal behaviour of these systems as the glycidylisobutyl-POSS was added, is discussed later.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
|